\(\frac{x-3}{504}+\frac{x-5}{1007}=\frac{x-1}{2018}+\frac{x-4}{403}\)
<=> \(\frac{x-3}{504}-4+\frac{x-5}{1007}-2=\frac{x-1}{2018}-1+\frac{x-4}{403}-5\)
<=> \(\frac{x-2019}{504}+\frac{x-2019}{1007}=\frac{x-2019}{2018}+\frac{x-2019}{403}\)
<=> \(\left(x-2019\right)\left(\frac{1}{504}+\frac{1}{1007}-\frac{1}{2018}-\frac{1}{403}\right)=0\)
<=> x - 2019 = 0
( vì \(\frac{1}{504}+\frac{1}{1007}-\frac{1}{2018}-\frac{1}{403}\ne0\))
<=> x = 2019
vậy x = 2019.